Explosive separation device



Jan. 25, 1966 w. L. WEBER ETAL EXPLOSIVE SEPARATION DEVICE Filed Jan. 23, 1965 0 mm Z 2 OA n. W W m4 MW M 4 MM L A 0 mm M f \N, 4 m F United States Patent M 3,230,885 EXPLUSIVE SEPARATl ON DEVICE William L. Weber, Levittown, and Anthony W. Dattilo,

Philadelphia, Pa, assignors to Thiolrol Qhemical Corporation, Bristol, Pa, a corporation of Delaware Filed Jan. 23, 1963, Ser. No. 253,476 6 Claims. Il. 102-49) The present invention relates to explosive type separation devices and more particularly to improvements in devices of the type used to releasably connect separate casing sections to each other.

While the separation device of the present invention may have other uses it is particularly adapted for separating successive sections of a multistage rocket engine while in flight. Explosives have previously been used to separate casing sections of rocket engines, but such devices have had a number of faults. One particular fault of such prior devices is that the explosive tends to tear rather than out the connected parts and requires an excessive amount of explosive to insure complete separation. Also the explosive is apt to produce a flowering of the edges of the cut casing sections. Such flowering con sists of a deformation of the edges of the cut material by the explosive force and such flowering is apt to destroy the contour of the gas stream issuing from the nozzle of the next stage of the rocket engine, in addition to impairing the aerodynamic stability of the next stage. Furthermore, the separation devices previously used do not produce any controlled force longitudinally of the casing to positively separate the severed sections.

One of the objects of the present invention is to provide an improved separation device which utilizes a shaped charge explosive for cleanly cutting a wall in a normal plane to insure complete separation of the parts with a minimum amount of explosive.

Another object is to provide a separation device of the type indicated which confines the shaped explosive charge in a closed annular chamber to provide a force longitudinal of the casing to insure positive separation of the severed casing sections as well as a reaction for the radial cutting force.

Another object is to provide an improved construction in a separation device of the type indicated which substantially eliminates flowering or deformation of at least one edge of the severed sections.

Still another object of the present invention is to provide a separation device of the type indicated which is of simple, compact and light weight construction, economical to manufacture and one which is reliable in operation.

These and other objects will become more apparent from the following description and drawing in which like reference characters denote like parts throughout the several Views. it is to be expressly understood, however, that the drawing is for the purpose of illustration only and is not a definition of the limits of the invention, reference being had for this purpose to the appended claims.

In the drawing:

FIGURE 1 is a side elevational view of a multistage rocket engine and showing the separation device of the present invention between adjacent sections;

FIGURE 2 is a transverse sectional view taken on line 2}2 of FIGURE 1 to show the separation device rigidly attached to adjacent sections of the rocket engine casing and the shaped charged located in a closed annular chamber formed by a peripheral groove in the device;

FIGURE 3 is a view similar to FIGURE 2 showing the thin wall section of the separation device cut by the shaped charge, the positive separation of the separate sections and the flowering at the edge of the discarded section of the rocket engine casing only, and;

FIGURE 4 is a sectional view of an explosive separation device of modified construction.

Referring now to the drawing, the present invention is shown applied to a rocket engine 5 having a forward section 6 and a rearward section 7. The forward end of section 6 has a rounded nose 8 and each of the sections has a combustion chamber 1i) and 11 and a converging diverging nozzle portion 12 and 13, respectively, at its rearward end. The combustion chambers and ill of the sections 6 and 7 each contains a propellant, not shown, which burns and produces gases that tlow through a nozzle 12 or 13 at a high velocity and produce a forward thrust. The sections 6 and 7 are arranged in tandem so that the propellant in the rearward section 7 burns first, and when completely burned out, ignites the propellant in the combustion chamber it) of the forward section. Each of the sections 6 and '7 comprises an enclosing casing having a relatively thin metal skin, and the casing sections are of the same diameter so that the rearward end of the forward section and the forward end of the rearward section abut each other as shown in FIG- URE 2.

In accordance with the present invention the abutting ends of the forward and rearward sections 6 and 7 of the casing are connected by an improved separation device 15. The device 15 comprises an annular strap or ring 16 having an inside diameter 17 to closely fit the outer peripheries of the casing sections 6 and 7. As shown most clearly in FIGURE 2, the strap 16 overlaps the abutting end portions 18 and 19 of the forward and rearward sections 6 and '7 so that the cleavage plane 2i) between the abutting sections is located between the ends of the straps. Strap 16 is rigidly attached to the end portions 1.3 and 19 of the abutting sections 6 and '7 in any suitable way such as by spot or rib welding, riveting, or the like. in the illustrated embodiment the strap 16 is attached to the sections 6 and '7 by the rows of circumferentially spaced rivets 2i and 22, respectively.

The strap 16 has an annular flange 23 at one end surrounding the end portion lid of the section 6 with holes through which rivets 22'. extend, see FIGURE 2, an intermediate section having a radial projecting boss 2 and an annular flange 25, similar to the flange 23, overlying the end portion 19 of the section 7. An annular recess or groove 26 is formed in the flange of the strap 16 adjacent the boss 24 to provide a thin reduced area 2'7 underlying the groove and of uniform reduced thickness around the entire periphery of the strap. This thin section 27 has substantially the same thickness as the skin of the rocket sections 6 and 7 to provide substantially the same strength in holding the sections connected to each other. By reference to FIGURE 2 it will be noted that the recess 26 is adjacent the boss 24 and the two have a common wall 28 therebetween. in addition, the boss 24 has an axially extending annular recess or groove 29 adjacent the top of the recess 26 and the bottom wall 31) of the axial recess 29 forms a continuation of the top or" the flange 25.

A cover ring 31 overlies the annular flange 25 of the strap 15 with a close fit and has an end 332, projecting into the axially extending recess 2-9. The rivets 22 extend through the cover ring 31 as well as the flange 25 of the strap and end portion 19 of the skin to rigidly connect all of the parts to the casing section '7. in addition, the cover ring 31 forms a closed annular chamber 26 and the free end 32 of the cover is interlocked with the boss 24 to provide a reaction to any radial force produced by pressure in the chamber, and opposed walls 28- and 34- at the sides of the chamber so that pressure in the confined chamber will produce a force acting longitudinally tending to separate the casing sections 6 and 7. It will he noted that the outer end of the nozzle wall 12 in section 6 is positioned adjacent the end thereof.

Mounted in the closed annular chamber 26 of the separation device 15 is a shaped explosive charge 35. The shaped charge comprises an annular ring of a mild detonating fuse type explosive 36 having an outer sheath 37 and a V-shaped recess 38 at one side overlying the thin wall 27 of the strap 15 at the bottom of chamber 26. The shaped charge type explosive 35 has a metallic lining 39 in the V-shaped recess 38 which is sufiiciently flexible to adapt the shaped charge to conform to the annular groove 26 and be covered by ring 31 to form a closed chamber. Such a shaped charge explosive, when detonated, produces converging forces which collapse the metal liner 39 in streams that merge and flow inwardly at high velocity between the inclined sides to cut the thin wall 27 cleanly in a thin cleavage plane. One form of the invention now having been described in detail, the mode of operation of the separation device is next explained.

When the casing sections 6 and '7 are initially assembled, the strap 16 is first telescoped over the end portion 18 of the casing section 6 and the row of rivets 21 inserted to attach the strap thereto. A length of the flexible shaped charge 36 is then inserted in the annular recess 26 to extend around the entire periphery of the strap with the V-shaped liner 39 overlying the reduced section 27 at the bottom of the recess. Cover plate 31 is then mounted on the annular flange 25 at the other end of the strap 16 with its end 32 projecting into the laterally projecting recess 29 in the boss 24 to interlock therewith. Rivets 22 are then driven through the cover 31, flange 25 of strap 16 and end portion 19 of the section '7 to join the sections 6 and '7 to each other through the strap in abutting tandem relation.

When it is desired to separate the sections 6 and 7 the shaped charge 36 is detonated. The shaped charge produces a shock and pressure build up in the closed chamber 25 at the same time that the metal liner acts in a radial plane to cut the reduced section 27 around the entire periphery of the strap. The shock and pressure build up is opposed by the interlocked cover plate 31 to insure a maximum cutting effect by the shaped charge. Furthermore, the pressure build up in the closed chamber 26 acts against the opposed walls 28 and 34 of the chamber to positively separate the severed parts of the strap and, as the parts of the strap are rigidly attached to the sections 6 and 7, positively separate the sections one from the other. Moreover, cover plate 31 prevents explosive back-blast damage to the regions opposite reduced sections 27. With the improved construction described above, it is estimated that only 25% of the energy generated is utilized in cutting the reduced section 19, which results from the use of a shaped charge, and a larger portion of the energy is utilized in separating the two sections. This is in comparison with the prior devices in which a mild detonating fuse (nonshaped) is used where 80% of the force generated is required to fracture the skin of the section. In addition, any flowering occurs on the portion 19 at the forward end of the rearward section "I to be discarded with no flowering occurring on the portion 18 of the section 6. This results from locating the explosive charge 36 rearward of the place where the ends of the sections 6 and 7 abut. As will be further observed by reference to FIGURE 3, the severed portion of the strap 16 connected to the forward section 6 is positioned forwardly of the cone formed by the gases escaping through the nozzle 12 so that it does not interfere with the stream and thrust produced thereby as is apt to be the case in prior art constructions. As the explosive force is applied to cut the fitting and as the rearward end of the front section 6 is connected to the fitting by rivets 21, no flowering can occur at the end of the skin of casing section 6.

A modified construction is illustrated in FIGURE 4 in which a rocket engine or other structure to be separated has a skin casing 49 having a continuous recess or groove 42 therein to divide the casing into sections 40a and 40b and a bulkhead 41 cooperating with the groove to divide the structure in sections. The bulkhead 41 has a flange 43 overlying the recess 42 to form a closed chamber 44 and provide a back up member. A shaped charge 45 is located in the closed chamber 44 to overlie the thin wall 46 at the bottom of the recessed groove the same as in the construction illustrated in FIGURES 1 to 3. The end of the flange 43 is connected to the casing 40 at a place corresponding With the forward end of the rearward section of a rocket engine by means of rivets 47.

The device illustrated in FIGURE 4 operates in substantially the same way as the device illustrated in FIG- URES 1 to 3. When the sections 40a and 4% are to be separated, the shaped charge 45 is detonated which cuts the reduced annular section 46 between the two sections. As the shaped charge 45 is locked in the closed chamber 42, the flange 43 of the bulkhead provides a reaction to the pressure and shock resulting from detonating the shaped charge. In addition, the pressure build up acts on the opposed side walls of the closed annular chamber 44 to positively separate the severed parts.

It will now be observed that the present invention provides a separation device utilizing a shaped charge type explosive for cutting in a single plane to separate the parts. It also will be observed that the present invention provides a separation device which utilizes the build up of pressure and shock experienced from detonating the shaped charge to provide a force longitudinally of the casing to positively separate the severed sections. It will still further be observed that the present invention provides a separation device of improved construction which substantially eliminate flowering or deformation of at least one edge of the severed sections. It will still further be observed that the present invention provides a separation device which is of simple, comp-act and light weight construction, economical to manufacture and reliable in operation.

While a single embodiment of the invention is herein illustrated and described it will be understoood that changes may be made in the construction and arrangement of elements without departing from the spirit or scope of the invention. Therefore, without limitation in this respect the invention is defined by the following claims.

What is claimed is:

1. An explosive separation device for a cylindrical structure having sections connected to each other in end to end relation, the means connecting said sections being annular and having a circular groove extending throughout the length of the connection between said sections to provide an area of reduced thickness therebetween, means overlying the open side of said groove to form a closed chamber, a shaped charge explosive snugly fitted in said chamber and having a V-shaped groove overlying said area of reduced thickness with said means overlying the open side of the chamber providing a reaction member opposing the exposive force of the shaped charge, and said shaped charge explosive having a liner in said V- shaped groove for cutting the area of reduced thickness in a medial plane between the inclined sides of said groove.

2. An explosive separation device for an assembled structure having separate sections connected to each other by a strap over-lying the seam between said sections, said connecting strap directly abutting the edge portions of the sections adjacent the seam and rigidly fastened to each section, said connecting strap having a groove extending throughout its length between the fastenings to the separate sections to provide a line of reduced crosssectionl area, a linear explosive charge in the groove and extending throughout the length of the groove, and a closure overlying the groove to form a closed chamber whereby to fracture the connecting strap along the line of the groove when the charge is detonated to release the separate sections and produce a force on the side walls of the chamber at right angles to the plane of fracture to positively separate the released sections.

3. An assembled structure having separate cylindrical sections connected to each other in end to end relationship by an annular strap, said connecting strap overlying the ends of the sections, rigidly fastened thereto, and having a circular groove extending throughout its length between its fastenings to the separate sections to provide a thin wall between the sections, a closure overlying the groove to form a closed chamber, and an explosive shaped charge in the groove and extending throughout the length of the groove, said shaped charge having a recess in one side converging walls overlying the thin Wall of the connecting strap to cut the latter circumferentially between its fastenings to said sections when the charge is detonated whereby the explosive charge produces a force in the closed chamber to positively separate the cut sections from each other.

4. In a multistage rocket engine, separate cylindrical casing sections for each stage, an annular connecting member overlapping the adjacent ends of the separate casing sections and rigidly fastened thereto, said connecting member having a circular groove to provide a thin section to be cut and positioned rearwardly of the forward section to overlie the forward end of the rearward section around its entire periphery, a closure overlying the groove to form a closed chamber in the member and mounted on and connected to one side of the member to slide with respect to the other side of the member, and an explosive shaped charge in the closed chamber and having a recess in one side with converging walls overlying the thin section, said explosive shaped charge cutting the thin section at the groove in the annular connecting memher and around its entire periphery when detonated at a location rearwardly of the joint between the sections and producing a force for positively separating the cut sections whereby any flowering ocurs on the rearward section underlying the thin wall being cut without deformation of the forward section.

5. A multistage rocket in accordance with claim 4 in which the connecting member is a ring and the fastening means are rivets extending through the opposite edge portions of the member and respective portions of the easing sections.

s. A multistage rocket engine in accordance with claim 5 in which the connecting member has a second groove extending axially of the casing sections: adjacent the first mentioned groove, said closure overlying the first mentioned groove is a ring surrounding a portion of the connecting member at one side of the groove and extending into the second mentioned axially extending groove at the opposite side of the first mentioned broove.

References Cited by the Examiner UNITED STATES PATENTS 2,543,057 2/1951 Porter 102-24 2,996,316 8/1961 Terhune 102-49 X 2,996,985 8/1961 Kratzer 102-49 X 2,998,771 9/1961 Mosier 102-49 3,017,836 1/1962 Guay 102--49 3,034,293 5/1962 Ferris et a1 102-49 3,067,973 12/1962 Halsey et a1. 102495 3,070,018 12/1962 Fahl 10249S 3,089,417 5/1963 Beyer et a1. 10224 3,108,540 10/1963 Fletcher 102--49 3,131,635 5/1964 Steinmetz et al l02495 BENJAMIN A. BORCHELT, Primary Examiner. SAMUEL FEINBERG, Examiner. 

1. AN EXPLOSIVE SEPARATION DEVICE FOR A CYLINDRICAL STRUCTURE HAVING SECTIONS CONNECTED TO EACH OTHER IN END TO END RELATION, THE MEANS CONNECTING SAID SECTIONS BEING ANNULAR AND HAVING A CIRCULAR GROOVE EXTENDING THROUGHOUT THE LENGTH OF THE CONNECTION BETWEEN SAID SECTIONS TO PROVIDE AN AREA OF REDUCED THICKNESS THEREBETWEEN, MEANS OVERLYING THE OPEN SIDE OF SAID GROOVE TO FORM A CLOSED CHAMBER, A SHAPED CHARGE EXPLOSIVE SNUGLY FITTED IN SAID CHAMBER AND HAVING A V-SHAPED GROOVE OVERLYING SAID AREA OF REDUCED THICKNESS WITH SAID MEANS OVERLYING THE OPEN SIDE OF THE CHAMBER PROVIDING A REACTION MEMBER OPPOSING THE EXPOSIVE FORCE OF THE SHAPE CHARGE, AND SAID SHAPED CHARGE EXPLOSIVE HAVING A LINER IN SAID VSHAPED GROOVE FOR CUTTING THE AREA OF REDUCED THICKNESS IN A MEDIAL PLANE BETWEEN THE INCLINED SIDES OF SAID GROOVE. 